Disclosed in U.S. Pat. No. 4,663,917 is a rotary packaging machine. The machine includes a pair of sealing jaws that are rotatably driven about parallel spaced generally horizontal axes. Associated with the jaws are stripper members which strip the bag material to inhibit product being located between the sealing jaws. Also associated with the sealing jaws are closer bars that engage the tubular bag material to again inhibit product being located between the jaws.
As the sealing jaws engage the tubular bag material they are generally travelling at the same speed as the bag material. However since the jaws are corrugated the bag material upstream of the jaws is accelerated. This in turn causes the bag material to move between the closer bars to the extent that the bag material initially above the closer bars passes through the closer bars to be located immediately below the closer bars just prior to sealing. This can result in product above the closer bars, particularly in the case of snack foods where there are crumbs, being pulled past the closer bars. This in turn can result in the location of product, such as crumbs, in the area between the sealing jaws. This results in an inferior seal and frequently in the bag material being punctured.
Previous packaging machines are described in patent specifications U.S. Pat. Nos. 6,367,230, 6,189,301, 6,052,971, 6,006,503, 5,881,539, 5,622,033, 5,622,032, 5,463,851, 4,999,974, 4,947,618, 4,759,170, 4,663,917, 4,566,253, 4,563,862, 4,532,753, 4,391,081, 3,849,965, JP 11180401, JP 8040403, JP 07132907.
With respect to U.S. Pat. No. 6,052,971, there is described therein a packaging machine provided with “wiper means” in the form of overlapping engagement portions that strip the bag material and cause the bag material to move upwardly relative to the sealing jaws. U.S. Pat. No. 4,566,253 describes a packaging machine that includes a series of interacting rollers that move the bag material upwardly to thereby strip the bag material by causing the bag material to move between a pair of stripping jaws. The interacting rollers reciprocate lineally in a direction generally transverse of the bag material. U.S. Pat. No. 6,189,301 describes a packaging machine having squeezing bars that are caused to oscillate angularly through approximately 45° to engage the bag material to inhibit product passing through the bag material and being engaged by the sealing jaws. The squeezing bars are mounted separately to the sealing jaws and do not rotate therewith.
The machines described in the above-identified patent specifications do not overcome the above-described problem.